Conventionally, in a semiconductor device manufacturing process, there has been employed a plasma etching method for performing etching by acting a plasma on a substrate (e.g., a semiconductor wafer) provided in a processing chamber. For example, in the semiconductor device manufacturing process, the plasma etching method has been used to form a contact hole in a silicon dioxide film or the like. Recently, it is required to form a contact hole having a fine diameter and a high aspect ratio (HARC (High Aspect Ratio Contact)) while suppressing occurrence of bowing in which a hole diameter becomes larger and maintaining a vertical sidewall shape thereof.
Japanese Patent Application Publication No. 2010-219491 discloses a technique for forming a hole having a high aspect ratio by etching an etching target film at a high etching rate while ensuring a good etching shape. In this technique, there is used a gas containing a halogen-containing gas represented by a fluorocarbon gas (CxFy) such as C4F8 gas or the like and additionally containing another gas such as Ar gas, O2 gas or the like. Further, a DC voltage is applied to an upper electrode of a plasma etching apparatus, and an ArF photoresist that is an organic film having a low etching resistance is modified by injecting high-speed electrons into a semiconductor wafer.
However, in the technique disclosed in Japanese Patent Application Publication No. 2010-219491, if the etching is continued, bowing occurs in the hole of the etching target film due to insufficient emission of secondary electrons and the high aspect ratio. In view of the above, the disclosure provides a technique for further suppressing occurrence of bowing.